[Victor]

"....It was a big boat. As I recall, someone once 'did the math' and proclaimed that it was, indeed, possible to hold two of each animal....."

Lest we forget, only land animals needed to apply. All other seagoing and many air species were largely unaffected.

[Wordsmith]

Lest we forget, only land animals needed to apply.

And freshwater fish as well. They would have all been killed by the salination of their water. So even though it's not mentioned in the Bible, Noah would have had to have tanks for fish.